A taxpayer that operated as an architectural, engineering, and consulting firm was allowed to claim the benefit of the sales tax exemption provided by Section 144.030.2(28). The section provides an exemption on purchases of computers, computer software and computer security systems by architectural or engineering firms headquartered in Missouri. In addition to having two physical locations that serve as places of business for its corporate headquarters, the taxpayer also has five offices in Missouri. The taxpayer’s facilities are integrated through central management and direction, common usage of resources and uniform professional practice. As a result, the taxpayer is entitled to claim the exemption set forth in Section 144.030.2(28), when making purchases of computers, computer software and computer security systems for its own use. (Letter Ruling No. LR5934, Missouri Department of Revenue, October 7, 2009)